Pyserial not getting response every time, input/output errors

Carsten Haese carsten.haese at
Tue Aug 12 22:11:02 CEST 2008

Rainy wrote:
> Hello!
> I'm having some trouble with pyserial package, I'm sending commands
> and reading responses from a custom pcb, and sometimes I get a proper
> response, at other times I get nothing, and sometimes I get about half
> of the response string with beginning cut off. About half the time an
> empty string is returned, the other ~half time good response, and more
> rarely I get partial response.
> When I try to use the same Serial instance to send/receive a few
> times, I end up getting an input/output error.
> Here are some examples:
>>>> ser = serial.Serial('/dev/ttyAM1', 115200, timeout=0.1)

One possible point of failure is that you're not supplying any 
parameters for the data format (byte size, parity, stop bits) and flow 
control. The Serial object will assume defaults, and those defaults may 
or may not be correct.

Try to find out what data format and flow control you should be using 
and set explicit Serial parameters accordingly.

Hope this helps,

Carsten Haese

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